If you have the 04 and up body style you can do the 4.8is look but if you have the 00-03 body you will have to get the 4.6is look

you can use either Crevier bmw online parts (Vahey) or Pacicfic BMW (edward) they ave good prices and have done this with a lot of customers..
Being that you are new you will see once you start this madeness that is called modification is becomes addictive.. It all depends on what you you are looking to achieve..
You may also look into the aluminum running board they are a nice look to add to the 4.6/4.8 look, and the 4.6/4.8is exhaust.

as for the wheels you have to check ebay for that i did see a guy once selling the silver replicas but i haven't seen too many out there most of the 4.8is wheels are chrome and most x5 owners thinks is too blingy, its a matter of personal preference
here is a link from the articles.. hope this helps

http://www.xoutpost.com/articles.php?...ticle&artid=13

http://www.xoutpost.com/articles.php?...ticle&artid=12

http://www.xoutpost.com/articles.php?...ticle&artid=15